Drier for printing presses



Feb. 9, 1954 R. G. ZIMMERMAN DRIER FOR PRINTING PRESSES 9 sheets-sheet 1Filed May 25, 1949 .mml

Inventor Pz'chard G.

mmerman Feb 9, 1954 R. G. ZIMMERMAN 2,668,700

DRIER FOR PRINTING PRESSES Filed May 25, 1949 '9 sheets-sheet 2 UML mvHRM Ina/en lor'L Richard G -mmerman /bg Cua, E219?, MJ* lA/ Feb. 9, 1954R, G, ZIMMERMAN 2,668,700

DRIER FOR PRINTING PRESSES Filed May 25, 1949 9 Sheets-Sheet 3 Im/entorRichard. G. )im rnerrnarl Feb. 9,

R. G. ZIMMERMAN DRIER FOR PRINTING PRESSES Filed May 25, 1949 9Sheets-Sheet 4 PRESS `SM5-51; Alva ConrnoLLe-n RosITIo/v EMERGENCY STOP,z FROM FULL .SPEED unmsn ASSEMBLY IMMEDIATELY RErRAcTs 'D Gas TuIrNL-oOrr Ama BuRNERs FLUSHED UNTIL BUTTON B PRESSE!) EMERGENCY STOP FRoMPARTIAL SPEED BURNER ASSEMBLY IMHEDIATELY RsrRAcTs Gns TuRIvEn OFF AnpBuRIvERs FLusHEo UNTIL Burro/v B hasta Fnass `SPEED AND CoIvTIQoLLgRPos/Tio TIME 1 Inl/enter fichar-d 6. immerrnan Feb- 9, l954 R. G.zlMMl-:RMAN 2,668,700

DRIER FOR PRINTING PRESSES Filed May 25, 1949 9 Sheets-Sheeil 6 Ina/entor Richard L'mmerh-ran Feb- 9, 1954 R. G. Z1MMERMAN 2,668,700

DRIER FOR PRINTING PRESSES Filed May 25, 1949 9 sheets-sheet v m/en for000000000000000000 .OAL QV` Richard brim-arman vel L OW\\\QM.\%\ E Wigmll mmfww bvm.

i .rv/ |Ql 1 \V 09.6%@

v MMBOJQ l9l Feb. 9, 1954 R. G. ZIMMERMAN 2,668,700

DRIER FOR PRINTING PRESSES Filed May 25, 1949 9 sheets-sheet s LI L3DRUM CONTACTS H0 TaR C /kcwr invent?" RL'charo( G. Zimmerman www Feb. 9,1954 R. G. ZIMMERMAN l 2,668,700

DRIER FOR PRINTING PRESSES Filed May 25, 1949 9 Sheets-Sheet 9 r A l 1 Inl: 4- l 1 i TLF I'T Bl I Uil gwen ,64 man l Inventor* Richard mmermanPatented Feb. 9, 1954 UNITED VDRIER FOB PRINTING PRESSES Richard G,Zimmerman, Lawrence, Kans.

ApplicationMay '25, 1949, Serial N 0.- 95,340'

(Cl. "26S-f3) 1.6 llainis. VYl

The present invention relates Lto printing presses vand moreparticularly rto aheaters .for .drying the ink film.

Throughout the course of printing :press de velopment there has been asharp line .of .des marcation between newspaper presses and magazinepresses. Newspaper presses enable high speed printing not only ofnewspapers but of otherr printed matter where quality .and appearanceare not of paramount importance. Such printing is done/on absorbentpaper and using non-drying ink. Because of the absorption of `the inkinthe pores -oi Mthe paper, the printing .fis characteristically dulland even the brighter colors are dead -and lifeless. Furthermorathe inklm 4must be "kept 'relatively thin since the absorbent quality of lthepaper-is limitedetherewise smearingwill result.

'For high vvquality printing #of heavy lms V.and brilliant colors it hasin the past Abeen necessary to'resort to the more expensive andcomplicated magazine press. Magazine printing -isfdone y*with driableink usuallyhav-ing avol-atile soiventand on coated ornon-absorbentfpaper.

Whenus'ing volatile lso'la'ent inks, 'the inlrmust be ys .rtiiiciallydried, this being conventionaiiy done by ,theuse'of steam drum-sor bygasburners. Steam drums 'are disadvantageous'since they are extremelyexpensive, oi heavyeonstructien, and require 'a large amount of'space,r`to `say 'nothing of the problem of furnishing steam. Infadditionsince. drying depends apen conducted heat, 'the velocity of the web mustAbe kept relatively low. Conventional gas burners-'alsohaverather-seripps limitations. Even'where the `flarne isplegvyedgdirectly `on the web, the dryingprocess issuperpial andineiiicient. Solvent is driven from the 'su-rface of vthe film and notfrom ythe body o f the lm or .from the pores 'ci the "paper, .and themaximum speed 'is -aconsequenbly limited An even more vimportantlimitation has to do swith operation at reduced .Speeds or upon.emergency shutdown. The normal heat output combined with the heatstored in the burners -and surrounding metal .parts ,frequently resultsscorching when the web is slowed'and `(3.0llflplete burnout when thelweb is brought to .ainorevsndden stop. The surface of the jini; alterdrying by .conventionalgas burners is A,often excessively rough to .thetouch .and the iiame ,playing ,on

the web :tends .to introduce wrinkles, giving .rise

to luneven Y.dry-ing .and Ascoren streaks. .ln ,addition, conventionalburner -araneements 4reallife frequent maintenance .and replacement dilev1to the extreme operating temperatures.

vBecause of `the :expense :.of a magazine press many printingestablishments have attempted to do 'high-quality worknn .La :newspaperpress by using inks having a volatile solvent. However, this involves so:many .disadvantages and corn.-v plications that it Ahas-never beforebeen accQr-h plished vfrom :a practical standpoint. in .the'first placethe vavailable room :in .the kvicinity .of .a newspaper press lisseverely restricted and 'cone ventional VAheaters for dry-ing 'the ink.cannotv be accommodated. Even when such heaters are used it-is=necessary vto reduce theispeed consider: ably from the normal valuelin order to insure that the ink is dried suiiiciently so as not tostick tothe successive roliers with which the printed face comesvintocontact. Iffenough heat .is ap.-

pl-ied to thepaper to dry-'the inkrat the normal web speeds, it lisfoundthat vthe paper will .in-.-Y

variably beseorchedfas the press is slowed down to a stop.

While it is known that radiant heatersare par: t-icularly -eieetive inVthe drying of iilms because of the -penetrationof fthe 'heat below theYsiniface of the Yrilrns, attempts to ruse radiant heaters in printingpresses have ybeenr fou-nd in general :to be disappointing; andimpractical,V the vpossibilities of scorching on ls`l1ut=down ibeinggreatly fin! creased. rvThe reason for l:this rwill be apparent when -itis -considered'that -a radiant lheater lby its very `nature f-mustoperate `in fthe fred-ff or radiating temperatnrevrange. Particularlywhen using gaS-iired radiant burners it is found that the radiatingelement ldoes not l--irnrnediately all to a safe temperature when thesupply nof fuel is eut on in Atl-ie normal way, but `continues lfor sometime to radiate .'.energy lat `a lrate which lis more 1than suicient tocause scorching. 4Any attempts -to `reduce the 'residual revelation bycuttingdownen theoapacity of the -fburnerswiilL of `coli-rise, producela corresponding. sacrifice .of heat under normal running conditions,particu;- 1arl-y the extremely high speed rconditions .characteristic ofa newspaper press. 1=Inanendeavor to overcome theseiects of Vtlc-ieresidual heat and to controlfthe Vheat under reduced speed conditionselaborate pivoting and llinllsalge iarr-ange.u ments have fbeen used solthat the 'burners are twisted "bodily .to vdirect the YYresidual iieat.away from the web. 'This ingeneral .requires that the individua/'lLburners be :manipuiated which :leads to mechanical -.complexity,`excessive cost large volumetric `.recluirements. Besides, Aany burner.movement ini/pires l jarring @ne material of which the radiatingsurfaces flfmed.

Where attempts have been made to mount conventional burner arrangementsin confined spaces nearby parts of the press are so overheated thatrubber rollers, lubricated bearings and other parts of the press are putin jeopardy to say nothing of the discomfort of the press operators.Additional difficulties arise from the problem of disposing of the fumesand inflammable condensate in the ducts.

Accordingly it is an object of the invention to provide an improveddryer for a printing press which is capable of large heat outputenabling drying of magazine-type inks at high speeds, even at speedsapproaching the standard operating speed of a modern newspaper press. Itis another object to provide a high capacity web drier in whichradiation and convectionare so embodies an improved burner arrangementin which the burners are mounted for movement as a unit, minimizing thenumber of moving parts. It is a related object to provide a dryer whichis safe and fool-proof in operation but which is nevertheless simple andstraight-forward and in which the cost per foot of drying the web isreduced to a minimum. It is a more detailed object of the invention toprovide a burner construction `and arrangement which is extremelylong-lived in spite of extreme operating conditions, and which requiresa small fraction of the replacement and maintenance demanded byconventional web dryers.

co-ordinated that scorching is avoided under all conditions, bothtransient and steady state, which may be encountered in the practicaloperation of a press. More particularly, it is an object to provide adryer employing radiant heat in which the temperature is brought to asafe level when the press is brought slowly to a halt or suddenlystopped as under emergency conditions. It is a further object to providea dryer which is of large heating capacity but Which neverthelessoccupies less volume than conventional dryers, being adapted forinstallation on existing newspaper and magazine presses with a minimumof modification thereof and Without danger of overheating the rubberrollers or any other parts of the press.

It is still another object to provide a gas-tired dryer for volatileinks in which the gas is more eiciently utilized than in conventionaldryers. It is a related object to produce a gas-fired dryer capable ofnot only evaporating solvent from the surface of an ink lm but which isalso effective to drive the solvent from the body of the film and fromthe paper itself, the freed solvent being then completely burned tofurnish additional heat and to prevent the solvent from passing into theatmosphere or from condensing in the exhaust ducts to form a re hazardand to endangerV exhaust fans and other equipment.

It is a further object of the invention to provide a dryer havinggas-fired burners with an improved arrangement for co-ordinating thesupply of gas and supply of cooling air with the speed of the web. Inone aspect it is an object to coordinate the degree of exhaust with thesupply of cooling air.

It is an object to provide a novel control scheme which actsautomatically upon varying the speed of the web driving motor to causethe valves supplying the burners as well as the burner positioning meansto go through a predetermined cycle of operations both upon increasingthe speed of the Web and upon slowing down the web prior to shut-downfor maintaining the web at a safe drying temperature. Y y

It is an object allied with the foregoing to provide a radiant dryer inwhich the latent heat that is stored under normal running conditions isnot only kept to a minimum but safely utilized during deceleration fordrying purposes, with t; e remainder of the latent heat being socompletely dissipated after the press comes to a stop that the danger ofscorching is eliminated. In one of its aspects it is an object of theinvention to provide a control scheme in which the timing of theoperations may be manually controlled by an operator.

It is a further object to provide a drier which Other objects andadvantages will become apparent upon reference to the speciiication andto the detailed drawings appended hereto in which:

- Figure 1 is a diagrammatic side elevation of amagazine press includingdriers embodying the present invention.

Fig. 2 isa detailed elevation of a web drier as.

used in the magazine press of Fig. 1 with the near side wall partially.removed to Vshow the burner assembly.

Fig. 3 is a more or less diagrammatic representation of the improveddryer installed on a conventional newspaper press.

Fig. 4 is a partial face view ofthe burner as` sembly. Y

Fig. 5 shows in perspective several successive burner faces.

Fig. 6 is a horizontal section of a line of v burners taken along theline -6-6 inFig. 2.

Fig. 6a is a fragmentary detail view along line tia-'6a of Fig. 6showing clamping means fory maintaining the burner manifold inassembledv position.

Fig. 7 is a vertical section looking along the` line 1-1 in Fig. 4.

Fig. 8 is an enlarged fragmentary section taken along the line 8-8 inFig. 4.

Fig. 9 is a rear view of the burner assembly Fig. 13 is a burner valvecontrol circuit as included in block form in Fig. 12.

Fig. 14 shows a control circuit for the motor which positions the burnerassembly and included in block form in Fig. 12

Fig. 15 shows graphically the operating sequence of the control circuiton starting up the press.

Fig. 16 shows a typical operating sequence on slowing the press to anormal stop.

Figs. 1'7 and 18 show the sequence during any emergency stop from fulland partial speed conditions, respectively.

Referring to Figure 1 there is shown a portion of a magazine pressZil.Theincoming web 2| passes over a first impression cylinder 22 and theiirst side of the web is printed by a plate cylinder 24. The printed'webthen passes down- Wardly into a dryer indicated generally at 25. Thisdryer is constructed in accordance with' the present invention and isshown in detail in the figures to be discussed. The web then passesaround `cooling drums 26, 21 and .into .a subsequent section of thepress so Vthat the remaining side .of vthe web Amay be printed. This isaccomplished by 'plate cylindersill, 3|, the web passing around anvimpression cylinder 32. If desired, .a conventional oil offsetarrangement 33rnay be .used in conjunction with the `impression cylinder32. The web subsequently passes upwardly through a .dryer 34 whichI issimilar to that .previously vreferred to and around cooling drums 35,36. The outgoing run cf the web may then 'befed into a slitter, cut-offcylinder and folder as required for putting the printed vmatter into laform for distribution.

Turning now to Fig. 2 the dryer 34 and the associated drums 35, y3| areVset forth in :greater detail. The dryer includes a burner assemblyI4|!! which iis vpreferably enclosed in `a box-iike housing 4| andarranged parallel to the vertical run 'of the web 2|. The burnerassembly includes lines of burners which extend horizontally and spacedvertically fromone another along the web. r'Ihese lines designated lil-30 inclusive, project radiant heat voutwardly in the direction of vtheweb. Arranged parallel to the web on the opposite side from the burnerassembly is a `back-up plate 6| which serves to reect the heat back ontothe web and to conduct away the unrelectedheat.

Before `proceeding with the more detailed structural features it will behelpful to refer briefly to Fig. 3 which shows an 'equivalentinstallation ina newspaper press. Corresponding elements will bedesignated with the same reference numerals used in the magazine pressbut with the subscript a. The printing unit 23a includes two printingcouples for printing on both sides of the web. The incoming web Zla isfed around an impression cylinder 22a and the web is printed on itsfirst side by a plate cylinder 23a.. The web subsequently passesupwardly through a dryer V25a and around water filled vcooling drums26a, 21a. The web next passes downwardly into contact with the secondimpression cylinder 32a which co-operates with a plate cylinder 30a. Anoil offset arrangement 33a rides in contact with the impression cylinder32a. After the second impression has been made the web rises verticallythrough a dryer Sta after which it passes about cooling drums 35a, 35a.After thus being printed on both sides, the web 2|a leaves the pressunit for subsequent slitting and folding and combination with othersimilar webs. Since the dryer installation may be substantiallyidentical in the two types of presses the subsequent discussion willconcern itself only with the installation as made in a magazinepress.

In accordance with one of the aspects of the invention means areprovided for generating radiant heat at refractory surfaces having lowheat storage capacity and for maintaining the burner mounting, the fuelsupply lines, and other metal objects within the region of radiation ata temperature which is extremely low compared'to that of the burner. Themanner in which this is VAaccomplished in the present instance will lbemade clear vby inspection of Figs. 2 and 5 to-S inclusive. Each'of theburners inthe lines 5| to V60 has a refractory face -pcrtion l1li whichis heated to brilliant red heat by the combustion of gas-air mix incontact therewith. Centrally arranged in the face portion and serving to`physically support it isia stem 1|.. lThe Alatter is threaded `into atubular manifold 12 of lrectangularsection which supports a L:lineofburners.- The .refractory burner .ma-` terial is vreinforced .bynmetalvwalls ,16, 11 which are .anchore'd'by screws or the like'tothemanifoldv12'. These walls rare preferably of light gauge metaland perforated toreduce heat trans` mission as well as Vthe amount ,of heat which may Vbestoredtherein. Direct .rearward -low yof heatfrom the burner .is reducedby spacing 'the` .Ihe manifolds for the various lines of burners are allmounted in intimate thermal contact with a ',backplate 13 which ispreferably formed of copper or othergood conducting metal. .In `con-ytact with the back` plate 13 aresuccessive convolutionsfof a vcoolingcoil 'Hl which conducts cooling water. The cooling coilmay also .beformed of copper sweated or brazed tothe conductive back plate '13.

In lorder to :minimize the direct transfer of heat Ato the back vplate13 and the horizontally arranged manifolds 12, the spaces :betweenthemanifolds are lled with high temperature inf sulation 83 havingextremely low heat storage capacity. Preferably such insulation'consists`of a series ofslabs or layers of asbestos, the layers being retained inlplace by the overhang of the edges of the burners as shown.

While it is possible to use various types lof burners 'having refractoryheat radiating surfaces the illustrated form of burner has been-found towork out most satisfactorily. The construction of theindividual burnersisset forth in some detail in Figs. 5 and 8. Here it will be seen thattheA face portion 16 -of the burners `isfcupped to vform a recess 80.Centrally positioned within therecess and at the end of the stem y'|| isa nozzle -8l. A concave deflector 32 .positioned opposite the nozzleserves to deflect the gas-air mix downwardly into the recess so that itis burned .in intimate contact with the refractory material. In axialsection the burners are generally cylindrical but attened on oppositesides sc thatV the individual burners may be stacked side vby side withthe recessesof successive burnersintersecting one another. This producesa -continuous band of radiation across the entire vWidth of .the webvand also facilitates lighting the burners Asince the iiame from a pilotwill quickly travel from one end ofthe line to the other. y

'I-o complete the discussion of the burner-.as sembly All, it includesat each 'end an upright channel 62 (Figo) which is covered with applate63 welded or otherwise xed thereto. The channel includesvcooling coils64. In order thatvan entire line of burners including its manifold maybe maintained in contact with the back plate yet readily .removed from ithe burner assembly, a clamp 65 lis used at each end ofthe vmanifoldwhich is so constructedfas to Xenable forward withdrawal. In the presentinstance the clamp, which is C-shaped, is `mounted on vthe plate :.63withits open side facing forwardly for receiving astub projection 66.The latter is 'butt Welded to the closed'end of the manifold 12.VAs'shown inthe detailed View Fig. 6a, the open side of the clamp -65 isspanned by means 'of a removableA bridgeBEWhich is maintained in placebysuitable bolts or the like 68. To facilitate withdrawalgofaburnerline, the pipes 69 supplying vgas ythereto extend rearwardly fromthe manifold and pass through suitable apertures in the back plate 13Vof the cover plate 15. It will be understood that each of the pipes 69is threaded so that it may be readily disconnected from the supply line.It will be apparent then, that any one of the lines of burners may bewithdrawn for maintenance or replacement merely by uncoupling the rearends of the pipes 69, removing the bridges 61 and drawing the selectedburner lines forwardly.

Since all of the burner assembly parts having any substantial heatstorage capacity are not only shielded against the direct transferenceof heat from the burners but are in intimate heat transferring relationto the cooling coils 14, it will be apparent that they will be kept at alow temperature. The surface presented toward the web by the burnerassembly is formed almost entirely of refractory burner faces andinsulating material, all having low heat storage capacity. Y

On the opposite side of the web from the burner assembly 43 is theback-up plate 6| providing a reflecting surface 85. For the purpose ofcompletely enclosing the web and defining an air flow channel about theweb as well as for preventing the escape of heat to the surroundingportions of the press, the back-up plate abuts a pair of side walls 81which are spaced from one another just sufficiently to enable theslidable reception of the burner assembly 40 between them. In order toconduct away the excess heat striking the back-up plate 6| and the sidewalls 81, cooling coils 86, 88 are provided. These coils are preferablyof copper or similar good conducting metal and are fastened in place bysweating or brazing. The side walls are preferably mounted for edgewisesliding on the press frame so as to provide access to the web forthreading and inspection.

It will be apparent from the foregoing that the burners and web aresurrounded by cooling coils arranged about all four sides. The manner inwhich these coils are supplied with cold water will be apparent oninspection of Figs. 9 and 10. Fig. 9 shows the arrangement of thecooling coils in the burner assembly while Fig. 10 is a diagrammaticview of the preferred form of circuitory system. It will be noted thatthe cooling coils 14 and B6 are arranged so that the successiveconvolutions are horizontal with the cooling water admitted at thebottom and drawn off at the top. This causes any steam which may begenerated in these coils to be immediately fiushed out and replaced bythe relatively cooler water. The latter avoids uneven cooling or hotspots and correspondingly reduces maintenance to a minimum. As shown inFig. 10 the water is drawn from a cold water supply line directly intothe cooling drums 35, 36 which are thereby kept at a very lowtemperature. The water exhausted from the cooling drums is then used inthe remainder of the system. The cooling coils 64 and 88 arranged alongthe side walls of the burner assembly are supplied with cooling waterindependently. Vertical convolutions can be used at this point since thetemperature is normally lower and there is less danger of developingsteam.

To keep down the heat radiated rearwardly from the burner assembly asWell as to even out the temperature thereof a light metallic cover plate15 is used. rhe spaces 19 between the coil convolutions may be lled withinsulation if' desired to reduce the temperature of the plate 15. Y

. In accordance with one of the aspects of the invention means areprovided for turning on the; burners and advancing the burner assembly4|!A upon accelerating the web and for turning oi theA burners andbodily retracting the burnerassem` bly away from the web when it isbrought to av to the web speed setting Will be discussed in av followingsection. Attention will first be given tov the mechanical positioningarrangement used in the present embodiment as set forth in Fig. 2.l Theburner assembly 4B is mounted on suitable Ways which permit the face ofthe burner assembly to move through a range 9|.

a reduction Worm gear 9s to apply torque to a cross-shaft 95.

obstructedly slots |02 are cut in the side walls 81.`

Turning attention now to the lower portion of Fig. 2, an air blast line|||l is arranged parallel to the lower edge of the burner housing and ina position to direct air upwardly in the space between the burners andthe web.

cussed in connection with Fig. 11.

Arranged at the upper end of the burner assembly to exhaust the coolingair as well as theI products of combustion of the gas and ink sol-` ventis an exhaust duct |20. This duct extendsthe width of the press andrhasa series of aperf tures or air inlets |24 along its lower surface. As

will be noted from the profile view of this duct in Fig. 2, theunderside is concavely formed so as to closely follow the curvature 0fthe cooling drum 35. In this way any vapor which tends tol cling to themoving web is eilectively withdrawn and does not escape into theatmosphere. *In carrying out the invention the exhaust duct |20 includesan additional set of apertures |22 whichv are substantially blocked oiTwhen the burner assembly Il@ is in its normal position closely adjacentthe web. However, upon retraction of the burner assembly the apertures|22 are successively uncovered in order to increase the effective ductarea and thus increase the capacity of the exhaust system. Vacuum isproduced in the duct |28 by means of a suitable exhaust fan |23 (Fig.10). As Will be understood by one skilled inthe Ventilating art, theexhaust fan will consume energy in accordance with the area of the inletduct. It will be clear, therefore, that uncover' ing the ducts |22serves automatically to increase' the volume of air exhaust from thesystem;

Movement in this range is affected by meansof ai burner assemblyadjusting mechanism indicated generally at 92. This includes a motor 93driving Rigidly mounted for rotation' With this shaft is a bell crank96, the latter being connected to the burner assembly 4U by meanslPreferably the line ||0 has a series of holes or nozzles spacedv alongits length capable of discharging a'largel volume of air. The valvearrangement for controlling the flow of air to the line'l l0 will bedisfeeding a, compressedl air line E33. thelines |39, |33 respectivelyare dam-pers. |34,; |35V whichA are. adjusted by a combustion conmeans`of anr air by-pass valve |31. Y that the main gas valve |3|V is shut01T, opening the air by-pass valve |31 will enable air at high Incarrying. out another. aspect. of they present inventionmeans areprovided for turningoff the burner lines. on` shutdown and fordischarging cooling air` directly through the fuel system of the'burnersv and into contact with the radiating surfaces thereof. Theeffect of this is toA reduce the radiating surfaces immediately to asafe temperature, the action being faciiitated by the low .specific heatof the refractory burner' material.

Inaddition thecooling air is heated by such. con-A tactand.-thevconvected'currentsof heated air are directed from the burner towardthe web. Thus, such. latent-heat as may be present in the burners iseffectively utilized to complete thedrying as the web is slowed andbroughtto a stop.

'Ihesystem here Used in accomplishing the above is setA forthdiagrammaticaliy in Fig, l1. 1 Gas issuppliedthrough a liner |3il havinga sole- .noid gas valve. tti. p the remaining v ves the system arecontrolled by means of the control circuit. (Fig. 12) which will bedescribedv in detail as the discussion pro- The latter valve as well asceeds. Air is supplied by means of a blower |32 In series4 with troller|236. The latter. is of conventional design capable of producing anoptimum fuel-air ratio for all rates of flow. The amount of gas-air miXat the discharge of the combustion controllerv may' be adjusted manuallyand left in an adjusted position, the generatedv heat being controlledby the other solenoid valves in thesystem. The' damper |35v in the airline is by-passed by velocity to pass through. the system for coolingpurposes.

Under normal operating conditions the gas f mixture passes through amixtureY supply line |40, through avalve. |4| and into-a header |42which supplies all of the burner manifolds with fuel. Interconnectingthe header |42 to the lines of burners are Valves |5.|-|5||respectively. The air blast line HU which directs air upwardly between.the burners. and the web is connected to the supply line. |40 bymeans ofa Valve |49;

in ordervto Vprevent the burners from blowing back when. the supply ofgas is cut on, each of thev burners: 54-60 is. provided with anauxiliary valve ld- |10 connected to any desired source'of. compressedair. The latter valves are electrically interlocked with the valveslill-|50 so that'after the Valve is shutoff compressed air is. suppliedto the burner for a short interval of time, on the order of rive'`seconds. -in which the interlock is eiected will bey made The mannerclear during the discussion of the control diagram in Fig. 112. Thecompressed air admitted by the.

auxiliary valves iSd-|! assists in bringing the temperature ofthe burnerfaces down toa value which will not produce scorching of the web. Al-

Y though not shown in the drawings it will be apparent toone skilled inthe art that name detectors androther safety devices may bel applied tocircuit forl causing operationY of thesev and asl sociated elements in apredetermined sequence isy Assuming l set-.forth in Figs. 12, i3 andv14. Fig. 12 is a diagram of the rcontroller circuit partially in blockformA while Figs. 13 and 14 set forth blocks in greater detail. Voltagefor operating the control circuits and motor isy obtained from the thruphase- A. C. lines LI, L2, and L3.

Prior tofdiscussing the functions of the control systemit will behelpful tov refer brieiiy` to the variousA circuit components' and tobring out the ning condition. Speed control is accomplished graduatedseries ofV twelve points.

relationship between suchv components and the speed. controller used inaconventional printing press. As. appreciated by one'skilled. in the art,a: printing press has a large driving motor and a small. drivingmotor-'which together act toY vary the speed of the webfrom standstillto full runrneans of a motor driven controller operated by a manualpushbuttonto` cover a series of speed points. 1n describing the presentembodiment it is assumed that the controller has a 1n practicing thepresent invention` a modified controller is used which has an auxiliarycontact drum having contacts which are operl.ated in sequence as the webspeed controller is moved in the increase and decrease directions. Thesecontacts include the prefix D andare shown along the left hand edge ofFig. 12. The

- present disclosure need not be burdened by a physical showing of thecontroller.. It will sunice to set forth in tabulated form. therelationship betweenv the speed` points and thev contacts as follows:

Increase speed Controller Point Drum Contact D2 closes. D3-1 closes.D4-l closes. D5 closes. D6 closes. D7 closes. D8 closes. D9 closes. D10closes. D11 closes. D12 closes.

Under conditions of decreasing web speed, the

drum contactsin Fig. 12 will be operated as follows:

Decrease speed' Controller Point Drumv Contact D12 opens. D11 opens. D10opens. D9 opone D8 opens. D7 opens. lD6 opens. {D opens.

D42 closes. D4-.1 opens. D3-2 closes. D3-1Y opens, D2 opens.

In order to further tie: in the present circuit with the normal speedcontrol of the web attention isy drawn to the fact that4 three oftherelays .in Fig., 12am-energized from asource of current external tothediaeram.. These. are a Stop re lay. an Orl7 relayandyan Oif relay.vThe Stop relay isenerg-ized Wheneverthe press is 7 5v :runnin-g,regardless whether it is driven by the drum contacts D6 to DIZinclusive.

jsmall or large driving motor. This relay drops outV whenever the StopVemergency button is operated or when a detector switch opens as a V'result of a web break. A suitable current source is provided so that theOn rlay is closed whenever the press is accelerated and the Off relay isclosed whenever the press is decelerated.

In order to locate the burner assembly suc- A cessively closer to theweb as the web speed increases, limit switches LSI, LSZ, LSB, and LSAIZCR, |3CR and MCR. The latter are controlled by the drum contacts in amanner which will become apparent as the discussion proceeds.

Y Referring now to the upper portion of the cir- 1 cuit diagram,solenoid valves IM, |49, I3| and |31 are shown connected to the contactsof a main relay IUCR. It will be recalled that the Q functions of thesevalves on being energized are as follows:

I III-permits iiow to burner manifold. HIS-admits compressed air to airblast line I ID.

` I3 I-turns on supply of gas from gas line.

I3'I-by-passes air around combustion controller.

Y' the Off condition by manual control, a pushbutton B is used which isconnected in a series with the contacts of a relay |8CR. The latter inconjunction with an off limit switch DLS on the press controlleroperates the restoring circuit in the event the operator does notoperate pushbutton B.

In order to operate the individual valves |54| 6|) inclusive foradmitting a combustible mix or air to the lines of burners 513-60,sub-control circuits |84|90 are employed. These circuits Y serve also tocontrol the auxiliary valves |64| 1U.

As will be apparent from inspection of the diagram, these circuits areunder the control of cuit diagram for the valve control circuit 184 istypical and is shown in detail in Fig 13. It includes a relay MICR foroperating the burner solenoid Valve |54 together with a relay MCR foroperating the auxiliary valve |64. In order to Y' hlimit the time thatthe auxiliary valve is open a time delay relay 40T is used having adelayed drop-out on the general order of ve seconds.

The contactor circuit for the motor 93 which adjusts the positioning ofthe burner assembly is indicated in block form at 200 and shown indetail in Fig. 14. It includes contactors UI and BI for operating themotor in the forward and reverse directions respectively. The motor isprotected by an overload device OLI and includes a brake to preventovertravel when the motor is de-energized. For the purposes ofsimplicity, only one adjusting motor has been included in the presentcircuit. It will be understood, however, that the invention is notlimited to the use of but one motor and includes the use of additionalmotors and limit switches for adjusting the remaining burner assemblieswhich v may be included in a complete set-up. 1 Any additional motorcircuits may be conneiiel Paral- The cir- Cil flz

lel across the supply lines LI, L2 and L3, 'and parallel connections mayalso be made to the y left hand or input side of the associated limitswitches.

The above completes the cataloging of the various elements in thecontrolcircuit. Since control circuits of this general type are wellunderstood by those skilled in this art, the present application willnot be burdened by a d etailed recitation of the electrical connections.The latter are specifically set forth in the drawings and the reasonsfor the same will become apparent in the discussion of the operatingsequence.

Control sequence uponl increasing speed M The operation of thecontrol'circuit just discussed for the increasing speed condition may bevisualized by reference to Fig. 15 which is a graph of controllerposition and press speed'as a. function of time. It will be assumed thatthe Apress ls started from rest and that the controller is moveduniformly from the first position to the twelfth or maximum speedposition. 'Ihis causes a progressively increased press speed. Because ofthe inertia of the rollers in the press, the press speed will lag themovement of the controller as shown. While the press speed is shown toincrease linearly, this is merely a simplifying assumption and theactual speed curve may have portions which are concave upwardly ordownwardly.

In accordance with one of the aspects of the invention the burnerassembly starts out from a position fully retracted from the web,movement of the press controller causing (1) at least a portion of theburners to be lighted, (2) the burner assembly to move up close to theweb and (3) the heat generated by the burner assembly to be increased asthe web speed setting is increased. In the preferred embodiment the heatproduced by the burners is increased by progressive, step-by-steplighting of additional burners so that under full speed runningconditions the burners will be fully on and so close to the web that thellame may actually graze the surface thereof. It will be appa-rent toone skilled in the art that the invention in its broader aspects is notlimited to an arrangement in which burners are turned on successivelybut would also include arrangements in which the increased heat outputis obtained by increasing the supply of gas-air mixture. The presentarrangement is preferred since variation in drying capacity is attainedincreasing the burner and, while the burner temperature remainsrelatively constant over the speed range. In Fig. 15 the stepped curveindicates the successive lighting of the burners at the variouscontroller points. The numbers applied to the steps indicate the numberof the burners (in the series BI-BU) which are in operation at eachpoint. The manner in which the above operating sequence has beenachieved in the present embodiment will be made clear by the followingstep-by-step description,

When the press is at rest the following conditions prevail:

Valve I3| closed-gas supply turned off.

Valve |4| closed-burner manifold closed.

Valve |37 open-air by-pass turned full on. Valve |49 open-air blastprovided by line I0.

'Preferably the press includes provision in the main drive circuit forinchingf This is conl/.emonally accomplished by an "inch button whichmay oe-operatedl eventhough the main 'controller is' set in the offposition. Thus,

the press cylinders -rnayy be--advanced,l say, for

threading the web without having any eiect closed, closure of D2causesrelay MECH. to be energized. The latter relay'remaing closedbecause vvof;a circuit which includes a normally closed con'- tacti onrelay' l'CR, a normally' open contact on the Stop relay, and; a normallyopenv or "sealing in contact on relaylCR. Aszsoon as relay l'CRcloses-the solenoid. valves are operated 'as'foll'owsz :Valveilclosedair by--pass turned oit.

Valve IM closed-airblast turned oil.v

Valve l 3 l. open-gas admitted from supplyA line.

Valve it! open-gas mixtureadmitted tofburner manifold;

'I'he' valves {5l-53 associated with the nrst three'. lines of burnersare' normally open. Burner lines l, 52, 53` fed by such valves are thuslit automatically upon admission of combustible'gas, lacontinuouslyburning pilot (not shown)y being 'associated With each of theY burnerlines. At this point burner valves IM-l-E are closed. Due

'to theV slow movement of the'web at this: time, the radiantheatfrom'the iirst three lines' oi burners is suflicient to producedrying even ythough the burners are in the fully retracted povsition.

On point 3', drum contact'DS-l closesto` run the burner assembly to itssemifretracted position approximately six inches from the Web. Thisresults because of the energization ofrelay l ICR which closes thecircuit to motor contact'or UI (see Fig. 14). When the burner assemblyreaches the six-inch position it automatically opens the VlimitswitchLS1 and the motor contactor U1 is dropped out, stopping the motor.

On point 4 drum Contact D4. closes.` to pick up relay IZCR. rihis causesthe motor contactor Ui. to closeresuiting in addi-tional" forwardmove-.mentV of the. burnerY assembly until the. contacter is. dropped out bythe limit switch LSB". At this timethe burner assembly isapproximatelythree inches from the web.v

Ori point 5 drum contactA Dcl'oses to energize relay 131GB.whichoperatesrin asimilar manner to. MCR yto runtheburner assemblytothefully advanced. or closed. position. Inths positiontheburner'cerarnio is about 11/24 inches iromtherweh. The 'web is by thistime moving at about onequarter speedand' only three lines of burnersare lit so that there is no danger of scorching; in spite of thecloseness of the burners.

When the controller is moved to point 6 the burner control circuit' its(see Fig; 13) is' enerisized. Relay liliCR is picked up which energizesT4 circuit: liishown inblock-form in: 12.1I This results in the turning-Onof burner' valve IE5; in the samefmanner as'. discussed. aboveforivalve. |54. kimilarly; theV .remaining valves tti60 areturnedononebyone1as the controller is moved from point 8 to theifullespeed positionat pointi12.

Operation of' dryer under high; speed' runningv conditions The Webf newris traveling i throughathe press at maximum speed and all of: theburners are ignited-.for applying both radiantl heat and con.- vected.heat to the: webv at close range. It will be helpful. yat this point to.observe the nature of the. drying which` takes place. Referring to-FigspZeg and.particularly-torig, gas iioWs into the manifoldifm fromthe', associated one of the valves Iii- 160, and; thence through thestem 'H and', nozzle 8i.. The gas flowing through thefnozraleIisdirected toward a cupz-shaped defiecting plate 237i:V and thenlbaclrvvardly` in., al smoothptoric l'ayeri along; the refractorymaterial forming the surface.z of the recessv all.y Burning of thegasadjacent' the refractory material of the burner causes such materialquickly to become red hot andthe radiantheatxtherefromis beamed alongthe burner. axis: in; the direction of the web.

Upon. striking the inkt lm the radiantenergy releases solvent fromthe.body; of the iilm.l as Well as from the surface. thereof'. In. addition,any of the solventv which yhasbeen, absorbedv inthe pores ofthe paperisy driven offV into the space surrounding: the Web. The solvent invaporform is ignited by the burnersV and; serves toincrease thetemperature oi the Webabove the point which would result from the actionof the burners themselves. Studies` havey shown that before the webcompletes. its journey through the dryer, substantially allV of thesolvent is liberated and hurried.v which noty only contributes to theeiliciency of, the dryerbut preventsthe solvent from beingdischarged:into: the atmosphere or condensing: in the' exhaust ducts to. create anre hazard. The' convected: heat andthe products of cornbustion aredrawnoi at the upper endet. the web bythe exhaust'duct i202 Since thelower: surface of the duct. 29' includes: apertures` |21. closelyfollowing the surface of the cooling drum 35, even the combustionproducts which are drawn along the web: are eiciently removed and no.harmful products are permitted to. escape. into. the` at'- mosphere;

A large portion` of" the heat produced by the burners is drawn.oi'through the exhaust system. Tozfully'understand the advantages ofthe:prestent construction, it will be helpful to trace the dispositionlofthe remaining heat. A certain portion of the heatA will be usedinraising the temperatureof the web itself. Thisheat is subsequentl'ysubtracted'from the web by the cooling vruins 35, 36. The radiated heatWhichpasses through the web strikes the back-up plate ETI (see Fig. 2).Because ofv the reflecting surface thereon most of'thisradiated heatissrefle'cted back onto the webwhere. it servesto: drive; off'additionalsolvent. Some: heat, however, passes into` the plate 85 whencev it isremoved. bythe cooling coil 36'.

Although the: sidewalls 8T and the ends.l ofi the burner assembly arenotin the direct radiation path,` a certain amountl of-A heatfrom the.burners will. ow to. the.r` ends` ofJ the burner. assembly.Thefheatiis-removed in this regi'oirbythe;y cooling eoilsll. 88;

Attention may next bergiven; totheow: offhea in the burner assemblyitself under normal operating conditions. As previously stated, therefractory surfaces of the burners are rendered red hot. Very little ofthis heat, however, travels through the refractory material since it isan extremely poor heat conductor. It might be expected that the metallicburner walls 16, 11 (Fig. 8) would conduct heat from the face of theburner'to the manifold. However, because of the thin cross section ofthese walls and because of the foraminated structure thereof, only avery limited'amount of heat will follow this path. As previouslydescribed, the burners are spaced at some distance from the manifold 12which supplies them. This space indicated at 18 in Fig. 8 is filled withinsulating material to minimize the direct rearward flow of heat fromthe burners. The only remaining metallic heat path, then, from theburner to the manifold is through the stem 1| arranged centrally in theburner and threaded to the manifold. However, it will be apparent thatif the cross section of this heat path is kept small, the amount of heatflowing to the Walls of the manifold may be correspondingly reduced.

In the present construction means are provided for keeping the auxiliaryportions of the burner assembly far below the temperature of the burner.This is accomplished in great measure by the 'back plate 13 whichengages the manifold 12 over an extensive area and which has sweatedthereto the cooling coil 1li. On each side of the manifold 12 the layersof insulation 83 prevent the passage of heat to which the latter issubjected as a result of convection and the reiiection of radiant heatfrom the back-up plate 6|. As a result of the foregoing structure,therefore, it will be appreciated that all of the parts of the burnerassembly which have appreciable heat storage capacity remain cool bycomparison to the burners which operate at a red heat. Since the back-upplate and the side walls are similarly cooled by water cooling coils,the heated space is eiectively isolated from the rest of the press.

The rubber rollers, mounted closely adjacent the dryer are kept at aboutthe same temperature as in presses not employing a dryer.

Control sequence-gradually decreasing speed In accordance with one ofthe aspects of the invention, the burner assembly is retracted and theburners are shut off and flushed with cooling air as an incident toslowing down the press. In the present embodiment a portion of thevburners operating during the normal running of the press are turned offone by one as an incident to decreasing the speed of the press, afterwhich Ithe burner assembly is retracted and the remaining burners areextinguished. Provision is quence or may be deferred until a later timein .65

the event that the dryer has not achieved its normal runningtemperature. In addition the flushing air is utilized to continue thedrying process, so that the latent heat removed in Abringing the burnertemperature down from the radiating range is not wasted but on thecontrary .isl usefully employed for drying. Finally, after the burnerassembly is retracted and the burners have been turned oi, a blast ofair is discharged :through space vacated by the burner assembly 75 andadditional exhaust ports are uncovered to conduct away the air in theair blast. The manner in which these novel functions are performed willbe apparent upon reviewing the step by step operating sequencecharacteristics of a normal and gradual shut-down. These steps are setforth diagrammatically in Fig. 16 which resembles Fig. 15 previouslydiscussed in that the numerals 1-12 indicate various controller pointsand the steps show the number of burner lines in operation at eachpoint.

With the controller at point 12, the conditions are the same as existedat the end of the increase cycle: the burners are all in operation andthe burner assembly is closely adjacent the web. As the controller ismoved to point 11, the solenoid valve |60 is turned off. This resultsfrom the fact that contact D|2 opens to drop out a relay in circuit |90,which relay corresponds to relay MICR shown in Fig. 13. Closing of thevalve |60 is accompanied by a timed discharge of compressed air throughthe auxiliary valve |10 associated therewith. The manner in which thisoccurs may be made clear upon inspection of Fig. 13, where thecorresponding circuit is shown. The normally closed contact on relay CRtherein completes a circuit through the timing relay 40T, resulting inthe picking up of relay MCR. The contacts of the latter relay cause theauxiliary valve |10 to open, thereby causing a discharge of compressedair through the burners in line 60. This compressed air has two effects:The primary effect is to blow out of the burner the combustible air-gasmixture, thereby preventing blow-back in the burners and manifold. Inaddition the air flowing through the burner nozzles serves to cool theface of the burner to the extent that the temperature of the exhaust airis suciently high to be useful in further dry- Aing the web at theexisting speed. The primary cooling effect, however, occurs at a laterpoint due to the effect of the flushing air.

At the end of a predetermined time interval, for example, five seconds,relay 40T drops out thereby opening the circuit to the relay MCR andturning off the valve |10. When the control is moved to point 10,contact D|| opens to deenergize the control circuit |89. This results inan operating sequence which is exactly similar to that mentioned in thepreceding paragraph. The net effect is to close the solenoid valvethereby turning off the burner 59 and injecting compressed air into theburner for a short space of time by opening the auxiliary air valve |69.

As the controller next is moved to point 9 and successively down topoint 5 the contacts in the series DH1-D6 inclusive cause shutting downof the burner lines 'S8- 54. In each instance an auxiliary source ofcompressed air is briefly connected to the burner.

When the controller reaches point 4 retracting movement of the burnerassembly occurs as follows: The drum contact D4-2 closes and since theoff relay contact is closed indicating that the press is beingdecelerated, relay MCR closes. A normally closed contact on the relayItCR opens the circuit to the contactor Ul (Fig. 14). Normally opencontacts in the relay MCR energize the opposite motor contactor Bl. Thiscauses the motor 93 to rotate until the burner assembly is fullyretracted, in the present instance to a distance of twelve inches fromthe web. At this point the burner assembly operates the limit switchLS4. This drops out contactor BI to stop the motor. Itwill be understoodthat when The flushing air, after acquiring the latent heat of theburners passes contact with the web to "taper off the drying operation.Simultaneously, dropping out of the Stop relay causes a normally closedcontact thereon to energize the relay MCR. This relay energizes thecontactor Bl to drive the burner assembly to its retracted positionwhere it is brought to rest by operation of the limit switch LSA. Whenthe controller rotates around to its off position, the 01T limit switchis operated to drop out the relays ISCR, HCR, and IDCR to terminate theushing and turn on the air blast from line l lli.

While the present construction causes the temperature of the radiantburners to be dropped suddenly, particularly under conditions ofemergency shutdown, itis important to note that drying is notterminating so quickly that undried web will pass through the dryer intocontact with subsequent rollers in the press. Instead, the latent heatof the burners is utilized to produce convection currents which producesurface drying of the film at a lower temperature level than is normallyproduced by the radiation. The necessity for removing undried ink fromthe rollers after an emergency shutdown is thus eliminated.

Provision is made for terminating the flushing and turning on the airblast before the press is brought to a stop. This is accomplished bypressing pushbutton B. The latter deenergizes the relay I8CR which inturn drops out relay HCR to establish the off condition which is asfollows:

Valve I 3l closed-gas shut oft.

Valve IM closed-burner manifolds shut off.

Valve I3? open-air by-passed around combustion controller.

Valve M9 open-air blast from line l l0 turned on.

In the event that the operator does not push button B to turn on the airblast, the relay l SCR will be dropped out, in any event, when thecontroller reaches its oir position. Conditions are then set upcorresponding to those listed above.

Providing the pushbutton B and its associated circuits for cutting offthe flushing process upon emergency shut-down adds iiexibility to theoperation of the dryer. If the press has only been in operation for ashort time and the dryer is not up to full operating temperature, theoperator may omit pressing button B. In this event the latent heat inthe flushing air will continue to have a drying effect on thedecelerating web even after the burner radiation is reduced to a, safepoint. However, where the press has been operated for a considerableperiod the operator may not wish to make use of the latent heat and maywish to merely reduce the radiation, following this immediately by anair blast to carry away as much of the heat in the dryer as possible. Insuch instance, the operator would press button B immediately as thepress begins its emergency shut-down. The eiect of flushing the burnersby air conducted through them followed by an air blast forming aprotector blanket has been found to safeguard the web against scorchingeven under the most abrupt conditions of shutdown.

In the above discussion it has been assumed that emergency shut-downtook place from the normal running speed. It should be noted, howeverlthat the emergency circuits are equally useful when the press isoperating at a partial speed or during the course of deceleration`Referring to Fig. 18 it will be assumed that the speed controller hasbeen moved down to point 8 when the This corresponds to a press'emergency arises. speed S. 'Ihe eiect of the emergency is to drop outthe Stop relay and to run the controller back to its off position. Thepress speed will suffer a correspondingly sharp decrease as indicated bythe break in the press speed curve. As before, the emergency will resultin the admission of flushing air to all of the burners to bring thembelow red heat, and the air blast may be turned on, if desired, prior tothe return of the controller to the 0H position by pressing thepushbutton B.

Since the pushbuttons A and B offer a certain degree of manual controlover the drying process, provision is made to insure that these buttonsare not operated at such times as will endanger the web. It will benoted, for example, that if button B is operated by accident withoutpreliminary iiushing, the press will stop and ushing will occurautomatically to bring the red heat of the burners down to a safe value.In the event that the press is accelerated to a partial speed point, forexample point 5, the burner assembly will be closely adjacent the web.Decelerating to point 4 will cause the burner assembly to be run out tothe retracted position. After the limit switch LS is operated in suchretracted position, the burner assemblies will be turned to the positiondetermined by the controller just as though acceleration were takingplace. For exampley if vthe controller has remained on point 4, the`burner assembly will automatically move forward to the B-inch position.

In spite of the high capacity of the dryer described above the volumewhich it occupies is only a small fraction of that required forconventional dryers used in the past. I'he dryer may be readilyaccommodated within the frame of a conventional magazine press withoutany substantial modification thereof. In the case of a newspaper pressthe dryers are suii'iciently `'small as to enable mounting above thepress unit. The supporting frame for the dryer in the latter instancemay be very light permitting the dryer to be installed directly on thepress frame. No additional floor space is consequently required. One ofthe factors contributing to the compactness of the present arrangementis the fact that the burner lines are xedly oriented in the burnerassembly. This not only facilitates cooling as Will be clear from theforegoing description but also enables the burner lines to be arrangedmore closely together and permits more efficient placement of insulationwhile enabling utmost simpliication from a mechanical standpoint.Regardless of whether the dryer is used in a magazine or newspaperpress, and in spite of the large amount of heat generated therein,practical experience has shown that heat is eiliciently confined and thesurrounding parts of the press are not subjected to high tempera-tureeven after many hours of continuous operation.

In the above description it has been assumed for simplicity that theburners are successively turned on and turned off at successive evenlyspaced controller positions. It will be apparent to one skilled in theart that the invention is not necessarily limited thereto and the pointsat 21 which the drum contacts are operated need not correspond to thenumbered controller points'.v In a practical installation the drumcontacts are so positioned that a sunicient number of the burner linesare turned on to produce the optimum dry'- ing effect for a givencontroller setting and web speed.

claim as my invention: l. In a dryer for a web a printing' press. aburner assembly comprising a back plate, burner lines arranged on saidplate and spaced from one another, each of the burner lines having alongitudinally extending manifold and a burner of .refractory materialsuperimposed thereon for producing radiant heat, said manifoldseachhaving an extended surface in contact with said back plate, hightemperature insulation having low heat storage capacity lling theinterstices between said manifolds, and a water coolingl line inintimate thermal contact with said back plate for maintaining said plateand said manifolds at a low temperature to minimize the stored heat ofthe burner assembly after a sustained period of operation.

2. In a dryer for a web in a printing press the combination comprising aburner assembly having a plurality of burner lines therein iixedlyoriented to supply radiant heat simultaneously to an extended surface ofweb, each of said burner lines including a metallic base having a i'aceof refractory material superimposed thereon which is cup-shaped in crosssection, means including a" nozzle for conducting combustible gas mixinto said cup-shaped face so that the latter becomes radiantly redduring combustion of the gas, a cooling pipe having cooling watercirculating therein and in intimate thermal contact with said base tomaintain it at a low temperature during operation of the burner, saidrefractory material having low latent heat under normal operatingconditions, and means for simultaneously turning oii the supply of gasand ad mitting cooling air directly on the radiating surfaces to quicklyreduce the temperature thereof upon shut-down of the press.

3. In a dryer for a web in a printing press a burner assembly includinga plurality of burners arranged substantially parallel to the web, saidassembly having a series of radiant gas burners mounted thereon anddirected toward the web, means for bodily advancing and retracting saidburner assembly to change the spacing between the burners and the web,and control means for (l) first turning on said burners in the assemblyin sequence and advancing the burner assembly toward the web as anincident to increasing web speed and 2) retracting the burner assemblyand turning off said burners in sequence as an incident to decreasingthe web speed.

4. In a dryer for a web in a printing press a burner assembly orientedsubstantially parallel to the web and having a plurality of radiantburners arranged in both directions therealong, lsaid burners beingfixedly mounted in said burner assembly so that the radiant heat'generated thereby is directed toward the web, a series of air jets alongone edge of the burner assembly and positioned to discharge a blanket ofair between the burner assembly and the web, exhaust means along theopposite edge of the burner assembly and means operating incident to areduction of speed of the web for supplying air to said air jets and forretracting said burner assembly away from the web to provide a channelof large cross section which extends substantially unobstructed 22between the jets and the exhaust means-for the accommodation of a largevolume of air in said blanket.

5. A dryer for a web in a printing press a burner assembly orientedparallel to the web. and having a plurality of radiant burners arrangedin both directions therealong, said burners including nozzles fortransmitting a combustible mix to the radiant face thereof and xedlymounted in said burner assembly so that the radiant heat generatedthereby is directed toward the web, and means operated as incident to areduction of the speed of the web for bodily retracting said burnerassembly from the web, turning off said source of gas, and supplyingcooling air to said nozzles for cooling said radiating surfaces.

6. A dryer for a web in a printing press including a burner assemblyextending the width of the web and oriented parallel thereto, theburners in said assembly being arranged therein so that radiant heat isdirected toward the web, exhaust means including exhaust ducts arrangedalong one side of the burner assembly and normally covered thereby whenthe latter is in normal running position, and means for retracting theburner assembly in a direction away from the web so that the exhaustducts are simultaneously uncovered thereby to facilitate the heatremoving action thereof with the result that the temperature of the airadjacent the web is lowered.

7. In a dryer for a web in a printing press the combination comprising aburner assembly having a box-like housing for said burner assembly, saidhousing including a plurality of gas burners nxedly mounted thereon andhaving a relatively flat end surface, said housing being open on theside toward said web so that the heat radiated from said burners isapplied to the web, an exhaust duct along an edge of said box-likehousing and arranged to be normally at least partially covered by theend surface thereof, means including a plurality of air jets arrangedalong the opposite edge of said housingr for directing an air blanketbetween the burner assembly and the web, and means for retractins saidhousing away from said web upon slow down of the web, such retractionserving to uncover an additional area of said exhaust ducts and servinglto increase the cross section ofthe air channel between said web andsaid housing to facilitate removal of the air from said air4 jets.

8. In a dryer for a web in a printing press a burner assembly comprisingin combination a plurality of burner lines arranged horizontally andspaced vertically from one another equidistant from the web, awater-cooled back plate, each ofv said burner lines including alongitudinal manifold of rectangular cross section, a plurality ofradiant burners of refractory material spaced along said manifold and incommunication therewith, the space between adjacent inanifolds beingfilled with insulating material' so that substantially the entire faceof' said burner assembly is composed of material having poor heattransmission characteristics, and means for normally clamping saidmanifolds into intimate thermal contact with the water-cooled back platebut permitting a selected burner line to be forwardly withdrawn as aunit for purposes of replacement or maintenance.

9. A system for supplying a gas-nred radiant burner in a printing pressweb dryer comprising in combination a source of gas, a source oi com-

